Petroleum or crude oil is a naturally occurring liquid found in the Earth Crust consisting of a complex mixture of hydrocarbons most of them alkanes of various densities. Some lighter hydrocarbons are considered natural gas or natural gas liquids, while denser hydrocarbons are more viscous, and the densest are paraffin wax and asphaltenes. It may contain other nonmetallic elements such as sulfur, oxygen, and nitrogen.
During production, crude oil flows in a mixture with water and solids (earth minerals). A fraction of this mixture is an emulsion containing oil water and solids. This emulsion constitute a series of problems for the handling, storaging, transporting and refining of the crude oil.
Emulsion forms upon cooling of the oil water mixture in combination with a significant amount of agitation and pressure differentials from the formation rock to the surface and to the storage facility. Chemicals contained in the crude oil and the water also act in the formation and stabilisation of emulsions. These chemicals in the oil can vary from long chain straight hydrocarbons of paraffinic type to complex hetero-atomic polycyclic and bi-polar molecules mostly carboxylic acids and naphthenic acids.
Sandstone formations from where the crude is extracted from provide an excellent base for emulsions. Fine silicon with oxygen compounds which are silicates form anionic crystallites which have a high affinity for water through hydrogen bonding, oil tends to surround these structures forming an emulsion. When the crude oil is being extracted, the pressure decreases, this leads to degassing of carbon dioxide from the formation water and will result in an increase in the pH value. Dissolved metals and bicarbonate in the water intervene in the formation of the carboxylic and naphthenic acids, which develops into an active stabilizing colloidal structures that enhance emulsion formation and also prevent existing emulsions from breaking.
Typical treatments for these emulsion include chemical addition such as de-emulsifiers and/or heating to promote destabilization and emulsion resolution. The use of boilers, furnaces and heat exchangers has been commonly used among the oil producers. Acid based demulsifier is the most common type of chemical used in the industry. Emulsions which are very hard to resolve like the ones formed by carboxylic and naphtenic acids; are difficult or impossible to treat with current state of the art.
Sludge is formed when heavy emulsions and solids settle inside crude oil storage tanks while waiting for further processing. Most of the existing process and methodologies are limited to emulsion resolution without considering the removal of the solid fraction. This causes a series of problems within the storage and transport systems.
Sludge represents a liability for the oil companies due to the environmental problems associated with their disposal even though it still contains high percentages of valuable crude oil. Thus, with further enhancement, a method for recovering crude oil which separates from emulsified fractions is desirable.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practice.